PROVIrlED. Purpc,se:The purposeof thisprogramisto continuean active, nationwidestudybegunin 1995of recipients of bloodproductsfrom donorswho subsequentlydevelopedclassicor possiblyvariantCJD to assessthe risk of"bloodbornetransmissionof these diseasesin the UnitedStates. Research Objectives:To systematicallycollectdata thatwillhelpdeterminewhetherclassicor variantCJD is beingtransmittedby bloodand bloodcomponentsinthe UnitedStates. Methods:The studywillbe conductedas follows: [unreadable] Maintainand increasecollaborativerelationshipswithUS bloodbanksto identifythe classicCJD blood donors andpotentiallythevariantCJD blooddonorsinthe UnitedStates andgatheravailable,relevant, medicalanddemographicinformationon suchdonors. [unreadable] Trace classicand variantCJD donorbloodcomponentstofinaldisposition. [unreadable] Maintainand enhancecollaborativerelationswithfinaldispositionsites andcollectvitalstatistics informationfrom pre-existingrecordsaboutrecipientsof the classicor variantCJD bloodcomponents. [unreadable] Maintainstudyinformationaboutthe recipientsofthe bloodcomponentsfrom classicCJD donorswho were previouslyidentifiedinthisstudyandcontinuetomonitorthese recipients'vitalstatus,includingthe causesof deathshouldtheydie. [unreadable] Developa planthat will(a) Searchnational,State,and localorganizationsdatabasesto matchvital static;ticsandcauses of deathfor thecomponentrecipients,includingutilizingnon-NationalDeath Index databasesto confirmthevital statusofthe componentrecipientsand (b) assessthe riskof blood-borne transmissionofCJD. Publishanddisseminateresultsof thestudy.